net: ti: fix CPTS driver build on arm

fix build errors:
drivers/net/ethernet/ti/cpts.c:266:12: error: 'ETH_HLEN' undeclared (first use in this function)
drivers/net/ethernet/ti/cpts.c:276:23: error: 'VLAN_HLEN' undeclared (first use in this function)

Fixes: 408eccc ("net: ptp: move PTP classifier in its own file")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Suggested-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpts.c

@@ -26,6 +26,8 @@
 #include <linux/time.h>
 #include <linux/uaccess.h>
 #include <linux/workqueue.h>
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
 
 #include "cpts.h"